1. Field of the Invention
This invention relates to hair care compositions with improved application properties and improved properties combining hold, flexibility and soft feel.
2. Description of the Related Art
The publications The History of Polymers in Hair Care (1940-present) and R. Y. Lochhead, Cosmetic & Toiletries, p. 23, 103 (1988) show that the development of hair styles and hair styling products has for a long time been influenced by the development of polymers and shaped by their novel properties.
From shellac to PVP, the properties have been adjusted to the desired hair styling effects and continually improved primarily through the use of copolymers in a targeted manner, through the individual monomer building blocks. Classic examples are the PVA/PVP copolymers in which hygroscopicity of the PVP is adjusted to an advantageous level through incorporation of vinyl acetates.
This constant development was also accompanied by more and more requirements which novel products have to satisfy. Examples of such requirements on a hair care composition are improved hold of the hair style (better setting), no sticky feel, no rigid hair, rapid drying times, ease of combing, hair volume, no weighing down of the hair, no water absorption through the polymer, ease of application in wet hair, ease of washing out with a shampoo and no flaking of the polymer film during combing.
On account of the multitude of requirements placed on such a product, sometimes with contradictory properties, it is therefore no wonder that there is a multitude of polymers for hair styling applications.
One dominant problem is the combination of good setting of the hair style and simultaneous nonsticky—or better—soft/natural feel of the hair. Especially if polymers for strong hold, such as acrylates, acetates, methyl vinyl ether/maleic anhydride or PVP, are used.
In order to achieve a flexible hold which still allows the hair style to move naturally and does not produce rigid hair with a brittle polymer film, copolymers of a combination of part acrylate and part silicone are used, where the highly flexible silicone part also affords a soft feel as well as high hydrophobicity.
There have been various approaches for achieving the combination of these building blocks and they have been described for hair styling applications, in particular hair spray applications.
Thus, the application EP 0 408 411A2 claims silicone copolymers with at least 15% by weight of hydrophilic monomer, for example, a dimethylaminoethyl methacrylate, in order to achieve setting. The U.S. Pat. No. 5,565,193 describes a formulation which additionally also comprises 0.5 to 15% by weight of a hydrocarbon solvent which has a boiling point of >105° C. The specifications WO 95/00106 and WO 99/55294 describe formulations with a water content of at most 10%. In addition, further patent specifications U.S. Pat. No. 6,350,439 B1, US 2002/0015681 A1, U.S. Pat. No. 5,618,524 and EP 0 412 704 B1 and also WO 00/51557 describe graft copolymers with monofunctional silicone macromonomers for use in hair styling products which achieve the combination effect described above.
Although these hair spray formulations containing silicone copolymers already lead to a certain improvement in the combination of good setting and styling with more pleasant soft hair feel, a further improvement in the individual effects in combination is required since it is requested by the consumer. Since, in addition to the chemical blocks which make up the hair styling polymers and can thus be brought to bear an influence on setting and soft feel, also the rheological behaviour of the hair spray solution, the droplet size of the spray and the viscosity of the polymer solution droplet have a great influence on the desired effects, a composition has to be found which leads to an improvement in the parameters and thus to an increase in the effects of setting and hold.
Low-viscosity compositions distribute themselves more readily on the hair surface on account of their better spreading. It is known that the lower the viscosity of the hair spray formulation on the hair, the more unnoticeable the sticky sensation and the more pleasant the hair feels.
A low viscosity of the hair spray solution, however, leads to relatively small droplet sizes during the spraying operation. Small droplets achieve weaker setting between the individual hair fibers and thus lower hold of the fibers, whereas larger droplets contribute to stronger setting and thus to a better hold of the hair style.
Optimal hair sprays are thus those which have large droplets during spraying but have a polymer solution with low viscosity that reaches the hair.
The droplet size can be adjusted to a certain degree through appropriate choice of valves and spray heads. Ultimately, however, the rheological parameters of the polymer solution and of the polymer film influence the principal improvement in the effects.
In order to achieve an improvement in the setting and flexibility while taking into account the described problems, the inventors in WO 00/51557 and US 2002/0015681 A1 describe a composition which comprises a combination of two different silicone graft copolymers. As a result, the composition has a high viscosity if it is released from the spray container with high shear, and a low viscosity when it reaches the hair and is subjected to low shear. However, a disadvantage here is that two different polymers have to be used for the formulation. The polymers have a high molecular weight, which leads to high solution viscosities and thus to difficult processing. The use of a single polymer which additionally has a lower molecular weight range would therefore be desirable.